So you feel like entering a new product key. Say you used that MSDN key in production, and now want to enter the product key. Well, according to Central Administration –> Upgrade and Migration –> Convert License Type, you can’t! The Product Key field is greyed out.

Of course, there is a way around this, but…

THIS IS UNSUPPORTED. DON’T DO IT.

Connect to your SQL Server and your Configuration Database. After taking a backup of your Configuration Database, run the following query:

Now, when you go to Convert License Type, you’ll notice that your product says it is a Trial, and it gives you the opportunity to enter a Product Key. Once the new Product Key is entered, your license will now expire one nanosecond prior to 1/1/10000.

Again, this is completely unsupported. In fact, the only supported way to change your product key is to rebuild your farm. So don’t do the above.